CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Operating revenue	$ 254,976	$ 266,307	$ 580,120	$ 645,494
Operations:
Water production costs	92,347	88,750	218,222	221,195
Administrative and general	34,216	33,328	105,177	99,425
Other operations	32,331	26,676	74,758	81,945
Maintenance	8,930	8,433	24,063	23,389
Depreciation and amortization	29,897	28,844	89,636	86,387
Income tax expense (benefit)	3,949	5,890	(1,366)	5,927
Property and other taxes	9,832	9,440	27,731	25,853
Total operating expenses	211,502	201,361	538,221	544,121
Net operating income	43,474	64,946	41,899	101,373
Other income and expenses:
Non-regulated revenue	4,535	4,573	13,643	16,772
Non-regulated expenses	(5,992)	(6,905)	(11,224)	(22,432)
Other components of net periodic benefit credit	4,776	3,737	14,753	11,516
Allowance for equity funds used during construction	1,387	1,004	4,146	3,021
Income tax expense on other income and expenses	(1,063)	(353)	(4,302)	(1,210)
Net other income	3,643	2,056	17,016	7,667
Interest expense:
Interest expense	13,482	11,891	39,791	34,972
Allowance for borrowed funds used during construction	(690)	(572)	(2,314)	(1,724)
Net interest expense	12,792	11,319	37,477	33,248
Net income	34,325	55,683	21,438	75,792
Net loss attributable to noncontrolling interests	(113)	(189)	(345)	(650)
Net income attributable to California Water Service Group	$ 34,438	$ 55,872	$ 21,783	$ 76,442
Earnings per share of common stock:
Basic (in dollars per share)	$ 0.60	$ 1.03	$ 0.38	$ 1.41
Diluted (in dollars per share)	$ 0.60	$ 1.03	$ 0.38	$ 1.41
Weighted average shares outstanding:
Basic (in shares)	57,704	54,007	56,695	54,063
Diluted (in shares)	57,740	54,042	56,731	54,104